1. Field of the Invention
The present invention relates to an oil supply device for an outboard motor that lubricates an intermediate speed reduction device provided on an intermediate portion of a drive shaft.
2. Description of the Related Art
WO 2007/007707 discloses an outboard motor having an engine installed in a vertical arrangement above a casing, with a drive gear provided at the lower end of a crankshaft of the engine and a driven gear provided at the upper end of a drive shaft extending downward inside the casing. In the outboard motor, the drive gear and the driven gear are meshed with each other in order to transmit the rotation of the crankshaft to the drive shaft.
Increasing the number of teeth of the drive gear relative to the driven gear allows the gears to serve as an intermediate speed reduction device, which reduces the rotation of the crankshaft before being transmitted to the drive shaft.
The gear transmission mechanism (intermediate speed reduction device) disclosed in WO 2007/007707 is provided immediately below the engine, and can therefore be easily lubricated using oil for engine lubrication.
Depending on the internal layout of the outboard motor, however, the intermediate speed reduction device discussed above cannot be disposed immediately below the engine, in which case it is conceivable to dispose the intermediate speed reduction device on an intermediate portion of the drive shaft. Since lubrication using engine oil is difficult in such an arrangement, it has been impossible to dispose the intermediate speed reduction device on an intermediate portion of the drive shaft.